Mini-LNG: gas where the pipeline does not reach

A gas pipeline is an excellent way to move gas and a poor way to serve a location that does not have one. For sparsely populated regions, isolated industrial sites and areas where building refuelling infrastructure is not viable, the alternative is to liquefy the gas, move it by road or water, and regasify it where it is consumed — a virtual pipeline.

That concept only works if the liquefaction plant at one end is small enough, cheap enough and simple enough to justify the volumes involved. Most of the interesting engineering in mini-LNG is about achieving that.

What the plant produces

A typical Glorinda mini-LNG module has a nominal production of 130,000 LNG gpd — about 210 TPD, or 490 m³/day. That corresponds to a natural gas feed of roughly 13,500 m³/h, and an energy equivalent of about 11,284 MBTU, 137 MWh or 284 TEP per day.

To put that in context: a 500 MW gas power plant consumes around 800 million m³ of natural gas a year. One year’s storage from a single mini-LNG module can cover roughly six weeks of that consumption — which is why these plants are as interesting for security of supply as they are for distribution.

The design decision that shapes everything: nitrogen

The cooling system operates on a closed cycle of nitrogen expansion, and this choice propagates through the whole plant.

Closed nitrogen cooling loops are among the simplest and most efficient refrigeration methods. Because the refrigerant is nitrogen rather than a hydrocarbon mixture, there is no need to adapt the refrigerant design to local weather conditions or to the composition of the natural gas. The cooling system can therefore be designed independently — easier, more cost-effective and more efficient than a mixed-refrigerant alternative.

It also removes a supply dependency. Nitrogen is produced inside the site from atmospheric air using a PSA module, so the plant does not rely on critical external resources. Plants operating on combined refrigeration require specific hydrocarbons that are not always readily available — a constraint that matters far more in a remote location.

And it is safer. Nitrogen leakage is neither hazardous nor toxic, and the rotating equipment is specified industrially against demand rather than to API requirements, which changes both cost and lead time.

What the plant does not need

The list of absent requirements is the commercial argument:

• Water. Apart from daily use by operators, no process water is required — heat is rejected by air coolers.
• Civil works. Concrete slabs or pads are the only construction required.
• Staff. The plant is fully automated and can operate without human involvement; in practice ten to fifteen employees are typical, depending on project conditions.
• Rotating machinery. The site has only two major rotary turbomachines, which extends life cycle and minimises maintenance, lowering operating expenditure.
• Permanence. The design is classified as prefabricated modules, so the entire system can be transferred to another location. The only loss is the construction investment — under 5% of the initial outlay.

That last point is unusual and worth dwelling on. An asset that can be relocated for less than 5% of its capital cost has a fundamentally different risk profile from a fixed plant, particularly where the gas source or the demand centre may change.

The rest of the chain

Liquefaction is one component. A virtual pipeline also needs a fleet of refrigerated transport tanks, portable liquid-to-gas conversion units and satellite regasification stations at strategic locations. The transport tanks connect to the regasification plant, where the LNG becomes gas again and is distributed through local pipelines.

Glorinda works across that whole chain: small and medium-scale liquefaction plants, LNG storage tanks, regasification terminals, virtual pipeline distribution, and floating storage and regasification units (FSRU) where the delivery point is coastal or offshore. Storage is typically double-shell bullet-type tanks with perlite filling, sized for two to three days of production.

Where it does not fit

Mini-LNG is not a substitute for large-scale liquefaction where a pipeline and export terminal already exist and volumes justify them. Its case is specifically the mid-range: enough demand to warrant liquefaction, not enough to justify conventional infrastructure, or a location where that infrastructure cannot be built at all.

The plant area is around 15,000 m² — preferably a rectangle of roughly 100 × 150 m — and electrical consumption runs between 6,200 and 6,500 kW. Those are the two constraints most likely to decide whether a given site works.